This program project is devoted to solving problems in structural biology, molecular recognition and enzymology by a combination of NMR spectroscopy and computational methods. The goal is to promote collaboration between investigators at the Harvard Medical School and in the Boston area with expertise covering biomolecular NMR, signal processing, computational chemistry, crystallography and biochemistry. By bringing together recent developments from all these fields, we will be able to make important methodological advances and obtain significant biological insights that could not be attained by an investigator from any one of these fields working in isolation. In component, #1, NMR and Data Reduction Techniques, Dr. Wagner will work with the co-PI's Drs. Hoch and Havel on the development of multidimensional multiple resonance techniques for studies of large proteins, together with improved procedures for processing, quantifying and making assignments from such data, with emphasis on parallel algorithms. In component #2, Structural Basis of Transcription Activation. Dr. Wagner will work with Dr. Harrison on the solution structures of N-terminal fragments of the transcriptional activator GAL4 by NMR, starting with the minimum size fragment that binds DNA and working upwards towards larger fragments that are capable of activation. In component #4, New Uses for Distance Geometry in Structural Biology, Dr. Havel will apply recent developments in distance geometry to the prediction of the structures of mutant/homologous proteins and macromolecular complexes by means of analogy with known structures. In component #5, Structure-Function Relationships in Cyclophilins, Dr. Walsh will expand upon his biochemical studies of the E. coli and human cyclophilins by applying NMR methods to mutant and homologous proteins as well as their complexes with the inhibitor cyclosporin A, with the goal of designing new inhibitors. In order to provide the necessary infrastructure for all of these projects, the following core facilities are proposed. Core A (Administration), to be managed by Dr. Wagner, will provide administrative support to all participants of this program project. Core B (NMR Technology and Biophysical Instrumentation), also managed by Dr. Wagner, will make the most recent developments in NMR technology, biophysical instrumentation and computational facilities available for use in all the above projects. Core C (Data Reduction), managed by Dr. Hoch, will develop, import and maintain the programs necessary for the processing of multidimensional NMR data. Core D (Modeling), managed by Dr. Havel, will provide an integrated and user-friendly package of computer programs that covers all aspects of computational chemistry, so that they can easily be applied to the participant's research projects.